The technologies of fiber optics and advanced composites have expanded to many applications in the aerospace industry. As dwindling energy supplies drive up the cost of aviation fuel, lightweight composites are replacing metal even in structural elements of aircraft. Similarly, fiber optic communication channels are increasingly replacing conventional electric wiring in aircraft and other structures. Among the various advantages of optical fibers over wires are the elimination of electromagnetic problems (i.e., noise pickup and incidental radiation of information desired to be kept secure): lowered raw material costs; elimination of potentially dangerous conductive paths and sparking problems in explosive environments: and weight savings.
Various examples of lightweight composite materials suitable for use in automotive and airplane bodies, boat hulls, furniture, building panels and other applications where high mechanical strength is essential may be found in U.S. Pat. Nos. 3,944,704, issued to Dirks: and 4,034,137 and 4,012,746, both issued to Hofer. Similarly, applications involving the embedding of optical fibers in a supporting matrix are shown in U.S. Pat. Nos. 3,728,521: 3,777,154: and 4,176,910, issued, respectively, to Borough, et al; Lindsey; and Noethe.
Both composites and optical fibers may be applied to structures employing light transmitting and receiving systems, such as aircraft, the composites being used to form structural components, and the optical fibers providing communication channels between the systems. Various difficulties have been encountered, however, in the installation and maintenance of optical fibers. Typically, the fibers are combined in bundles, sheathed, and held in place by appropriate retention structures which may be formed integrally with an associated structural component. Such a scheme is unsatisfactory for several reasons. While sheathing affords some protection, the enclosed fibers may still be broken if struck or compressed. Further, the required retention structure represents an added effort for molding the component. Various post molding steps, such as drilling and cutting apertures through which the fibers must pass, must be performed, resulting in increased manufacturing costs. Also, such apertures degrade the strength of the structure and introduce passages for leakage of gasses and liquids.
Thus it is seen that it would be of great advantage to eliminate the problems associated with segregated structural components and optical fibers.